/*
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package demo.parallelcore;

import java.util.Map;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class Selection extends DemoHelper {
    /**
     * Mapping customer to its total order price, only customer whose total
     * order price is bigger than bigValue will be put into the map
     * 
     * @param  bigValue customer's total price low limit
     * @return a map which map customer to its order price
    */
    public static Map<Customer,Double> bigOrderCustomers(double bigValue) {
        Function<Customer, Double> orderTotal = 
                c -> c.getOrders().stream().
                        //map order to order price
                        mapToDouble(Order::getTotal).
                        //calculate total price
                        sum();
        //A predicate which filter customer whose total order price is greater
        //than bigValue
        Predicate<Customer> bigOrder = c -> orderTotal.apply(c) >= bigValue;
        return customers.parallelStream().
                //filter customer whose total order price is greater than bigValue
                filter(bigOrder).
                //grouping customer to a Map which key is customer, value is 
                //total order price
                collect( Collectors.toMap(Function.identity(), 
                        orderTotal));
    }
}
